A bipolar junction transistor (BJT) is a type of transistor that relies on the contact of two types of semiconductor for its operation. BJTs may be used as amplifiers, switches, or in oscillators, for example. Charge flow in a BJT is due to bidirectional diffusion of charge carriers across a junction between two regions of different charge concentrations. The regions of a BJT are typically called emitter, collector, and base. A discrete transistor has three leads for connection to these regions.
The bandgap is the energy difference between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. There is virtually no bandgap in most metals, but a very large one in an insulator or dielectric. In a semiconductor, the bandgap is small. Technically, the bandgap is the energy it takes to move electrons from the valence band to the conduction band. A bandgap reference voltage is a voltage reference based on this property.
A high precision bandgap voltage reference is a temperature independent voltage reference circuit widely used in integrated circuits, usually with an output voltage around 1.25 V.
A translinear circuit is a circuit that carries out its function using the translinear principle. These are current-mode circuits that can be made using transistors that obey an exponential current-voltage characteristic—this includes BJTs and CMOS transistors in weak inversion. By using this exponential relationship, this class of circuits can implement multiplication, amplification and power-law relationships, for example.
Other features of the present embodiments will be apparent from the accompanying drawings and from the detailed description that follows.